A body implantable lead assembly forms an electrical connection between a patient's anatomy and a pulse generator such as a cardiac pacemaker, an implantable cardioverter defibrillator (ICD), an appetite or pain suppression device, and the like. The lead assembly includes a lead body comprising a tubular, flexible biocompatible, biostable insulative sheath or housing, such as formed of silicone rubber, polyurethane or other suitable polymer. One example of a lead body is a lead having a tip electrode, a ring electrode and one or more other electrodes disposed along the lead body. In many configurations, the lead includes a coaxial conductor extending about a central lumen of the lead body. Another example of a lead body is a cardioverter/defibrillator lead that includes a sensing ring, a shocking right ventricle (RV) electrode, a shocking superior vena cava (SVC) electrode and a tip sensing/pacing electrode. The lead includes a multi-lumen housing, each lumen of which carries a separate conductor through the lead housing to each of the sensing ring, RV electrode, SVC electrode and tip electrode.
In certain applications, coil conductors may be used, while in other applications single or multi-strand cable conductors may be used to connect the pulse generator at the proximal end portion of the lead with the corresponding electrodes at the distal end portion of the lead. In some existing multi-lumen lead bodies, a combination of a coil conductor and one or more cable conductors may be utilized.
To facilitate connection of an implantable lead to a compatible pulse generator, the proximal lead connector is inserted and secured in the device header. This provides the mechanical and electrical connection between the implantable lead and the device. For the current generation cardiac leads, the design includes a connector pin which is terminated to an inner coil conductor by welding and/or crimping. The coil conductor extends from the connector to the distal tip of the lead.
Current generation IS4/DF4 leads utilize a coil conductor (extending about the core lumen) to connect the tip electrode to the connector pin and utilize cables to make additional terminations. Termination crimp sleeves are attached to the proximal end of each conductor cable. The termination crimp sleeves are welded to termination pins on the distal end of conventional IS4/DF4 connectors to provide an electrical and mechanical connection. The IS4/DF4 connectors have three distal termination pins to facilitate connection with three termination crimp sleeves and cable assemblies. The IS4/DF4 leads utilize an inner conductive coil to provide an electrical connection from the connector pin to the lead tip electrode. In active fixation leads, the conductive coil is also used to provide torque through rotation of the connector pin to extend and retract the helix fixation mechanism. In passive fixation leads, the conductive coil acts as an electrical conductor and as a pathway for delivery tools (such as guidewires and stylets).
However, existing connector assemblies used with the above noted lead configurations experience certain limitations. For example, the connector pin, which is rotatably located in a header mating face of the connector assembly, exhibits a certain amount of axial movement The axial movement of the connector pin affects the position of the connector within the header which changes the relative alignment between contacts on the connector assembly relative to mating contacts in the header. The axial movement of the connector pin limits manufacturing tolerances associated with other contacts on the connector assembly.
A need remains for a connector assembly for a lead body comprising multiple cable conductors wound in a spiral manner about the lead body without an inner coil conductor to provide select characteristics in lead delivery and lead body durability.